1. Field of the Invention
This invention relates to apparatus and methods for the treatment and processing of semiconductor wafers.
2. Prior Art
Semiconductor wafers are utilized in the modem electronics industry for the production of very large scale integrated (VLSI) circuits and Ultra Large Scale Integrated (UlSI) circuits and chips and the like. Such semiconductor wafers must go through a wide variety of high manufacturing standards steps in order to produce a perfect semiconductor product.
During that production process, the wafers must be treated by a series of sequential steps. The processing of these wafers may include oxidation, ion implantation, thermal annealing, deposition, etching, passivation and packaging. The thermal annealing and solder reflow may be some of the most important steps in VLSI/ULSI. Some prior art processing operations may include the use of a continuous drive belt through a furnace heating and a cooling zones. Such a system, however, requires large clean rooms, and they operate under expensive operating conditions. Other prior art processing may be done on semiconductor wafers in a batch process. Uniformity and consistency of a product is difficult to maintain or achieve in these processes. Such prior art operations in either a belt or batch process are also often very expensive and very complicated.
It is an object of the present invention to overcome the disadvantages of the prior art.
It is a further object of the present invention to provide a wafer processing operation which simplifies the automation needed to effectively and efficiently handle and treat a semiconductor wafer.
It is still a further object of the present invention to provide a semiconductor wafer processing arrangement which minimizes the equipment size required for this operation.
It is yet a still further object of the present invention to provide a wafer processing arrangement which minimizes the cost of such wafer processing.
It is still yet a further object of the present invention to provide an apparatus for the continuous treatment of semiconductor wafers in a clean and controllable manner not found in the prior art.
The present invention relates to a wafer processing arrangement for the sequential isolated treatment of semiconductor wafers. The processing arrangement comprises a frame support for a wafer process table and a wafer feed and removal robot arrangement thereadjacent. The wafer process table comprises a plurality of housing covers each positioned on a stationary upper plate as part of a treatment module for each position in the process of treatment of the semiconductor wafers.
The wafer process table includes a stationary lower housing platen surrounding a central transmission drive unit which indexes an indexable rotary index plate between a plurality of treatment modules through the sequential steps in the treatment process at the wafer process table.
Each step in the process is accomplished as the intermediately disposed rotary index plate rotatively indexes through a series of positions, which positions register with the upper plate and the housing covers associated therewith, and the stationary lower housing platen with its respective treatment modules.
The stationary lower plate includes for each position in the process, an opening therethrough with a lower portion of the processing or treatment module thereattached. The processing module attached to the lower side of the stationary lower plate consists of a lower cup or housing. The lower housing has an upper edge defined by an annular lip which is secured to the periphery of its respective opening in the lower plate of the process table. The lower plate and lower housing is stationary with respect to the upper plate of the process table and frame.
The intermediate rotary indexing plate is arranged between the upper plate of the process table and the lower plate supporting the outer lower cup shaped housing at each processing module therearound. The rotary indexing plate has spaced apart openings on which a vertically liftable annular wafer ring is disposed. Each vertically liftable annular wafer ring has a plurality of circumferentially spaced openings therethrough to provide a fluid communication between the stationary upper chamber at each processing module and the outer lower housing of each processing module. Each wafer ring has at least three radially inwardly directed wafer support pins extending therefrom. Each wafer pin has a radially inwardly directed shoulder. As the rotary index plate advances rotationally from treatment module to treatment module in sequence around the wafer processing table, a robotic arm loads and unloads a semiconducter wafer at the particular loading and unloading station in the sequence. The wafer is placed upon the upper side of the shoulder of the wafer support pins which extend radially inwardly from the inner edge of the wafer ring. The shoulders on the pins provides lateral control to a wafer supported on those pins as the index plate is rotated.
Each processing module location has a lower support housing associated therewith. The lower support housing includes a support column extending therethrough. A wafer treatment plate is arranged on the upper end of the support column extending through the support housing. The treatment plate is arranged within a vertically displacable isolation chamber. The support column moves the isolation chamber and the treatment plate arranged therewithin, into vertical supportive contact with a semiconductor wafer held by the wafer support pins extending radially inwardly from the wafer ring supported on the indexing plate. The treatment plate, preferably of circular configuration, has a corresponding radially inwardly directed grooves arranged therein, for spaced enclosive receipt of the radially inwardly directed wafer support pins. As the treatment plate is moved vertically upwardly, it contacts and lifts the wafer slightly away from the wafer support pins to permit full engagement of the treatment plate with respect to the wafer support pins.
During this part of the process, the isolation chamber, which has an O ring around its upper peripheral edge, engages the lower side of the wafer ring. The lower peripheral edge of the inverted upper chamber has an O ring therearound. As the treatment plate is driven upwardly, the rising lower chamber lifts the wafer support ring slightly and presses the upper side of the wafer ring against the lower periphery of the housing cover or stationary upper chamber to define an isolation chamber therebetween which is thus formed between the stationary upper chamber and the upwardly movable isolation housing.
The treatment plate may comprise heating elements therewith, or cooling elements, therewith, so as to touchingly engage and more rapidly heat the semiconductor wafer thereon or touchingly engage and more rapidly chill that semiconductor thereon depending upon which position that particular semiconductor wafer is at in the process table.
A treatment port may be arranged through the stationary upper housing, to provide a vacuum to the isolation chamber, or to provide a chemical vapor deposition (CVD) or a physical vapor deposition (PVD), an RF generator, or a plasma therethrough or a combination thereof for treatment of that particular semiconductor wafer at that particular module in the apparatus.
The support housing beneath the outer lower housing may include a bellows to permit the longitudinal advancement and withdrawal of the support column of the housing while maintaining the ambient relationship within the isolation chamber. A treatment plate and isolation housing lift and retraction mechanism is also arranged within the support housing to provide the vertical advance and vertical withdrawal of the treatment plate from a semiconductor wafer supported on the wafer support pins on the wafer ring. A vacuum and/or sensors may extend through one or more of the support housings to provide suction to a wafer on the plate for holding purposes. Sensors may provide temperature information about the wafer and or the wafer thereon. Indexed rotational movement of the rotatable index plate advances subsequent semiconductor wafers to each respective treatment module for sequential treatment as that index plate is rotated about its central axis. The robotic loading and unloading of semiconductor wafers occurs from a radially outwardly disposed location with respect to the process table. This peripherally disposed wafer manipulation, instead of from a center of table location, permits simpler indexing mechanism and greatly simplifies the loading and unloading of the semiconductor wafers at that particular loading and unloading module location in the sequence at the process table.
The treatment plate has a radially directed channel spaced at least partially thereacross. The depth of the channel in the treatment plate is greater than the depth of the grooves for accommodating the wafer support pins thereon. This permits the robotic loading and unloading arm to move or remove a wafer onto the radially newly directed support pins and then subsequently downwardly therefrom to permit the support of that wafer on those support pins without disturbing that semiconductor wafer and without engaging the treatment plate.
Thus what has been shown is an apparatus for the serial processing of semiconductor wafers from an initial loading of an indexable rotatable plate through a circumferential arrangement of locations at separate treatment modules thus through an unloading operation of that semiconductor wafer after its treatment process. Each independent treatment module effects an isolation chamber processing to permit ambient conditions to be effected upon that semiconductor wafer at that particular location in the process table. By this stepped indexing and complete isolation as each individual wafer is individually processed, treatment times may be minimized and treatment effectiveness may be maximized and equipment costs may be reduced due to the simplicity of the operational features of the present apparatus.
The invention thus comprises an apparatus for the treatment of semiconductor wafers, comprising: a supportive frame and a process table arranged on the supportive frame, the process table comprising a stationary upper platen and a stationary lower plate; an intermediate indexing plate rotatively arranged between the upper platen and the lower plate; a wafer support pin attached to the indexing plate for the support of a wafer by the indexing plate; an upper housing arranged on the upper platen and an outer lower housing arranged on the lower plate; and a displacable lower isolation chamber disposed within the outer lower housing, displacable against the indexing plate to define a treatment module between said upper housing and the lower isolation chamber in which the wafer is treated. The apparatus includes a wafer supporting treatment plate arranged within the lower isolation chamber, for controlled rapid treatment of a wafer within the treatment module. The treatment plate may have a heating element therein. The treatment plate may have a cooling element therein. The process table may have a plurality of treatment modules arranged circumferentially therearound. The wafer support ring may be vertically displacable with respect to the indexing plate, to permit a tight seal to be arranged between the lower isolation chamber, the wafer support ring and the upper housing. The treatment plate may have a vacuum line arranged therein to permit a wafer carrier thereon to be suctioned against the treatment plate during a treatment process. The upper housing may have a treatment port arranged therethrough to permit a wafer supported therebelow to be treated by a treatment selected from the group consisting of: chemical vapor deposition, physical vapor deposition, ion implantation, plasma enhanced chemical vapor deposition, and radio frequency radiation.
The treatment plate may have a plurality of grooves arranged on an upper surface thereof to permit the upper surface of the treatment plate to be raised above the level of the pins. At least one of the grooves may comprise a channel for the receipt of a robotic arm therein. At least one of the grooves is deeper than the remainder of the grooves in the treatment plate. A controllably movable support column may be arranged through the lower housing to permit the treatment plate and the lower isolation chamber to be vertically displaced. The upper housing and the lower isolation chamber form a wafer treatment module when the lower isolation chamber is raised against a lower side of the indexing plate. A portion of the indexing plate adjacent the wafer may be supported thereon by a wafer ring, and wherein the wafer ring may include the radially inwardly directed wafer support pins. The wafer support ring may have a plurality of openings spaced circumferentially therearound to permit fluid communication between the upper housing and the lower isolation chamber.
The invention may also include a method of preparing semiconductor wafers, comprising the steps of: arranging a stationary upper platen and a stationary lower plate on a frame, with the upper platen having a plurality of upper housings spaced circumferentially therearound, and the lower plate having a corresponding plurality of lower housings spaced circumferentially therearound; rotatively supporting an indexable plate between the upper platen and the lower plate; loading a wafer to be treated onto an arrangement of support pins extending at least part way across the opening on the indexable plate; rotating the indexable plate between the upper platen and the lower plate for successive treatment process locations for treatment of the wafer; and isolating the wafer on the index plate at each treatment location for independent controlled access and treatment of the wafer thereat.
The method may include the steps of: lifting a treatment plate into direct supportive contact with the wafer to begin a step in the treatment of the wafer; arranging a plurality of grooves on the treatment plate to permit the pins to be received therewithin, to allow the wafer to be supportively touched by the treatment plate; arranging a lower isolation chamber within each of the lower housings; moving the lower isolation chamber with respect to the lower housing to define an isolated treatment module between the upper housing and the lower housing; moving the treatment plate and the lower isolation chamber simultaneously to initiate treatment of a wafer supported on the pins; heating the wafer in the isolated treatment module after the wafer has been lifted from the pins; chilling the wafer in the isolated treatment module after the wafer has been lifted from the pins; introducing a further treatment to the wafer at a successive isolated treatment module after the treatment plate has been lowered from support of the wafer and the index plate has been rotated to a subsequent position between the stationary upper platen and the stationary lower plate.
The invention may also include a method of preparing semiconductor wafers comprising one or more of the following steps of: rotating a wafer bearing indexing plate into alignment between an upper housing on a stationary upper platen and a lower housing on a stationary lower plate; lifting a treatment plate into supportive engagement with the wafer borne by the indexing plate; and isolating the wafer to provide an individual sealed containment thereof during a treatment process applied to the wafer; loading the wafer onto the indexing plate by a robotic arm arranged radially outwardly of the indexing plate, to minimize the complexity of such loading; arranging an opening on the indexing plate for receipt of the wafer; placing a plurality of radially directed pins on the periphery of the opening, to enable the pins to support the wafer during rotation of the indexing plate; forming grooves on an upper surface of the treatment plate to permit the pins to be received therein to allow the treatment plate to directly touch and support the wafer during treatment thereof; enclosing the treatment plate in a displacable lower isolation chamber; and moving the lower isolation chamber into sealing engagement with the indexing plate as the treatment plate is lifted into supportive engagement with the wafer; placing a wafer ring onto the indexing plate to support the wafer on the indexing plate; and arranging a plurality of radially directed pins on the wafer ring to support the wafer within the wafer support ring; lifting the wafer support ring from the indexing plate to properly engage the wafer by the treatment plate.
The invention may also include a semiconductor serial-processing table comprising: a movable indexing plate supported between a stationary upper plate and a stationary lower plate, the upper and lower plates each having a plurality of housings opposing one another, each of the opposed housings defining a wafer treatment module therebeween. A vertically displacable treatment plate may be arranged within each of the opposed housings arranged to support a wafer for treament thereon; the indexing plate may include a plurality of openings therethrough in vertical alignment with the opposed housings on the upper and lower plates, to permit a wafer to be arranged therewithin. A liftable wafer ring may be arranged within each of the openings in the indexing plate to permit the upper and lower opposed housings to define an isolation chamber. The lower housings may be vertically displacable with respect to the lower plate. The lower housing may include an outer lower housing secured to the lower plate.